Bit weird, but all of the user data for one of the accounts on my PC has disappeared. When I click on the Documents or Pictures button from the start menu, it says that the folder is empty. Also, when trying to access the data from the admin account, the user doesn't appear in explorer (other accounts still appear). The user still comes up on the login screen and the account can still be accessed by logging-in as usual.
Any ideas?

Thanks

Could also be worth running a malware scan - there's a couple of "file recovery" type scareware software that hide user's files and folders.